(1) Field of the Invention
This invention relates to novel 4-cyanopiperidine derivatives and a process for the preparation of same.
(2) Description of the Prior Art
The compounds of this invention are useful as intermediates for the syntheses of quinuclidine derivatives. Quinuclidine derivatives are in turn useful as synthesis intermediates for medicines, chemical reagents, etc. Their syntheses are however not easy due to their unique structures. Synthetic processes for quinuclidine derivatives have been reported, for example, in Helvetica Chimica Acta, 194, 1672-1679 (1954) and ibid, 195, 1680-1688 (1954). In this literature, 4-cyanoquinuclidine was synthesized by way of N-methyl-4-carbamoylpiperidine, N-methyl-4-cyanopiperidine and N-methyl-4-cyanoquinuclidine when 4-carbamoylpiperidine was employed as a starting material. This synthetic route however involved problems such that many process steps were required because N-methylation was effected at the beginning and demethylation was conducted at the end and the yield of the conversion step of from piperidine to quinuclidine was as low as 17%.